
.clear {
  *zoom: 1;
}
.clear:after {
  display: block;
  clear: both;
  content: '\0020';
  visibility: hidden;
  height: 0;
}
.float-left{
  float: left;
}
.float-right{
  float: right;
}

/**
*   center ele for unknowned size 
*/
.center-unknown{
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(50%,50%)
}

/**
*   center text box 
*/
.center-text {
  text-align: center;
}
/**
*   center for horizon
*/
.center-block {
  margin: 0 auto;
}